Hydraulic apparatus



Nov. 25, 1952 E. H. BORN 2,619,041

HYDRAULIC APPARATUS Filed Sept. 14, 1946 5 Sheets-Sheet 1 IIVVEIVTOR ELLIS H. BORN NOV. 25, 1952 BORN 7 2,619,041

I HYDRAULIC APPARATUS Filed Sept. 14, 1946 3 Sheets-Sheet 2 FIG. 6

INVENTOR. ELLIS H. BORN Nov. 25, 1952 BQRN 2,619,041

HYDRAULIC APPARATUS Filed Sept. 14, 1946 3 Sheets-Sheet 3 I85 I74 Si 3? a;

190, i Lu '7 I l we v l INVENTOR. ELLIS H. BORN Patented Nov. 25, 1952 UNITED STATES PATENT OFFICE Denison Engineering Company,

Columbus,

Ohio, a corporation of Ohio Application September 14, 1946, Serial No. 697,042

4 Claims.

This invention relates generally to hydraulics and is particularly directed to fluid pressure energy translating devices of the axial piston type which are capable of use either as pumps or motors.

An object of this invention is to provide a fluid pressure energy translating device so constructed that objectionable noises, heretofore resulting in pumps of this character, will be eliminated, the mechanism to which this invention is directed, being such as to eliminate the noise regardless of the pressure at which the device is being operated.

An object of this invention also is to provide a fluid pressure energy translating device having means for causing the equalization of pressure between the piston chambers and the ports with which these chambers communicate immediately prior to communication therewith so that no shock or vibration, which might cause noise. will result. This invention contemplates the building up or reduction of pressure in the piston cylinders as they approach the inlet and outlet ports to the end that the pressure in these chambers will be substantially equal to the pressure existing in the ports approached thereby.

In most devices of this character the pistons are mounted for reciprocation in a cylinder barrel which has sliding engagement with a valve plate containing inlet and outlet ports. As the cylinder barrel revolves, the piston chambers alternately communicate with the inlet and outlet ports; during this communication the pistons are reciprocated by means, commonly termed swash plate or cam means, disposed to provide an inclined track for engagement by the pistons. Due to the inclination of this track high and low points thereon are provided which register with the section of the valve plate between the inlet and outlet ports thus when the cylinder barrel revolves, the pistons pass over these high and low points which cause the direction of reciprocation of the pistons to reverse. By varying the inclination of the swash plate or cam means, the displacement of the pistons in the piston chambers may be varied to vary the volume of fluid delivered by the device.

An object of this invention is to provide means for equalizing the pressure in the piston chambers, as they pass from the inlet to the outlet port or vice versa, with the pressures in these ports approached thereby, the means being such as to be unaifected by the change of inclination of the swash plate or cam means to vary the volume of the device.

Another object of the invention is to provide a fluid pressure energy translating device having a cylinder barrel and cam means for moving pistons in the cylinder barrel, the cam means being inclined in two directions arranged substantially at right angles to one another, the inclination in one direction serving to cause the pistons to move fluid into and out of the piston chambers while the latter are in communication with the inlet and outlet ports, the other inclination serving to cause movement of the pistons in the piston chambers while the latter are moving from the inlet to the outlet port and vice versa.

A further object of the invention is to provide an axial piston pump or motor with a cam or swash plate so inclined as to cause the pressure in the piston chambers to increase while approaching the outlet or pressure port and decrease while aoproaching the inlet or suction port and to provide means in connection with such ports to prevent the pressure in the piston chambers from exceeding that existing at that instant in the inlet and outlet ports, the pressure in the piston chambers thus being equalized to prevent shock or vibration when the piston chambers register with the ports.

A fluid pressure energy translating device of the character mentioned in the foregoing object in which means are provided to cause an equalization of pressure between the piston chambers and the inlet and outlet ports is shown in my co-pending application Ser. No. 577,290, filed February 10, 1945, of which this application is a continuation in part.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the invention is clearly shown.

In the drawings:

Fig. 1 is a vertical longitudinal sectional view of a fluid pressure energy translating device formed in accordance with the present invention.

Fig. 2 is a horizontal longitudinal sectional view taken on the plane indicated by the line IIII of Fig. 1.

Figs. 3 and 4 are developed views separately illustrating the effective cam tracks produced by tilting the cam member in two directions and the relation of the cam tracks to the ports in the port plate. While these cam tracks are shown separately in the drawings, it should be understood that the actual cam track is a composite curve embodying both of the cam tracks shown. Fig, 5 is a front elevational view of the valve plate showing the same in a slightly indexed position.

Fig. 6 is a fragmentary horizontal sectional view of a modified form of pump or motor embodying the invention.

Fig. '7 is a transverse sectional view taken through a still further modified form of pump embodying the present invention.

Referring more particularly to the drawings, the numeral 20 designates the pump or motor formed in accordance with the present invention in its entirety. In the form of the invention i-llustrated in the drawings, the pump or motor is provided with a body 2|,v a head 22, and an end cover 23 which are connected to form a housing 24. The head 22 has a central opening 25, which opening is enlarged at its outer end to receive bearing means 26. In the instant pump the bearings rotatably support a sleeve 21' to which is pinned, for rotating movement therewith, the main shaft 2'8 of the pump. One end of the sleeve 21v has a shoulder 30 formed thereon while the opposite end is threaded to receive a lock nut 3L By adjusting the lock nut, the shoulder 30 may be drawn into close engagement with one of the bearing elements 26, the lock nut engaging the other element to prevent undue longitudinal movement of the sleeve in the bearings. The main shaft 28 projects outwardly beyond the bearings and is provided with a key 32 to permit a pulley, a motor, or other driving. device to be attached thereto. The outer end f the central opening is closed. by a cover 33 having an oil seal 34 disposed therein to prevent the escape of fluid around the shaft.

At its inner end the head 22 has a short boss 35, the inner end of which is faced for engagement by a disc-like member termed in this application the valve plate 36. The inner end of the boss 35 has a pair of openings 31 and 38 formed therein, these openings communicating with passages extending to the opposite sides of the head. 22 and terminating in finished pads 40 and 4| to which threaded pipe connectors are bolted or otherwise secured, these connectors receiving the ends of inlet and outlet conduits 42 and 43. The valve plate 36 has arcuate inlet and outlet ports 44 and 45, respectively, extending therethrough, Whichports communicate with the inlet and outlet openings 3'! and 38 formed in the head as is customary in devices of this character. The valve plate has a circular boss '46 formed on the face exposed to the interior of the housing 24 and this boss is engaged by the inner end of the cylinder barrel 4?.

This barrel member has a plurality of piston chambers 48 disposed in a circular row around the axial center of the barrel and extending parallel thereto. The barrel is also formed with a central opening 50 having key slots or splines by which the barrel is connected for rotary movement with the inner end of the main shaft 28. As in the above mentioned co-pending application the cylinder barrel is provided witha skirt portion 52 extending beyond the end of the cylinder barrel and journalled in an antifriction roller bearing 53 supported in the body 2|. The cylinder barrel and skirt may be formed integrally or of two parts as illustrated which are fastened together with screws or other securing elements 54. From the foregoing it will be seen that when rotary movement is imparted to the outer end of the shaft 28, the cylinder barrel will also be revolved to alternately register the piston 4 chambers with the inlet and outlet ports 44 and 45 respectively.

Communication between the inlet and outlet ports and the piston chambers registering therewith is secured through small openings or ports 55 formed in the end of the cylinder barrel. These ports 55 are arranged in a circle having a radius equal to the radius of the arcuate inlet and outlet ports so that registration or communication will be maintained throughout the full length of the inlet and outlet ports. This communication will be interrupted when the piston chamber ports 55 move across the cut-off portions or spaces separating the inlet and outlet ports.

While the chambers register with the inlet and outlet ports, fluid is drawn into and expelled from the piston chambers 48 by pistons 56 disposed for reciprocation therein. These pistons are of cylindrical form and are provided at their outer ends with. spherical heads 5! on which bearing shoes are mounted for universal movement. These bearing shoes have one fiat surface 60 for sliding engagement with the smooth flat face 6| of a cam 5.2 supported in the end cover 23'. This sliding engagement is maintained by a disc 63 which engages shoulders 64 formed on the bearing shoes 58. The disc is resiliently urged toward the. cam by a spring-pressed plunger 65 slidably positioned in the inner end of the main shaft 28; this plunger has a ball and socket connection withthe disc to permit relative move ment between these elements as the cylinder barrel revolves.

As in my co-pending application Ser. No. 575,864, filed Feb. 2 1945, the flat surfaces of the bearing shoes have recesses formed therein, which recesses communicate by way of passages formed in the bearing shoes and the piston with the interior of the piston chambers. This arrangement provides for the admission of fluid under the pressure existing in the piston chamber and the port with which it is communicating, to the recess formed in the bearing shoe whereby a pressure-balanced condition will be secured between the bearing shoes and the cam surfaces. This pressure balance minimizes wear and force necessary to effect the operation of the motor or pump thus increasing its efii'ciency.

To effect the support of the cam'in the end cover 23, .thelatter is provided with a plurality of rollers 66 disposed for engagement with an arcuate surface 61 formed on the back of the cam 62, this arcuate surface being struck from a center. disposed on the axis of rotation of the cylinder barrel in aplanepassing through the center of the universal joint between the pistons and the bearing shoes, this plane also passing through the center of the universal joint between the plunger 65 and. the disc 63. With this arrangement the cam will be adjusted about an axis passing through the axis of rotation of the cylinder barrel in substantially parallel relation to the face of the valve plate. Since the axis of turning movement of the cam is disposed substantially symmetrically with the inlet and outlet ports, the forces tending to disturb the adjustment of the cam will be equally divided and will therefore offer a minimum resistance to the adjustment. To facilitate th assembling and dismantling of the device, the cam is resiliently held in engagement with the rollers 66 by a spring pressed strip 68 carried by the end cover 23. As shown in Fig. 1, the strip 61' is bowed arcuately to offer minimum resistance to the adjustment of the cam. This strip engages a pin 68, carried by a bifurcated yoke secured to the rear surface of the cam 62. A block H is pivotally supported between the forked end of the yoke 10 and is similarly connected to the inner end of a stem 12 positioned for sliding movement in a packing gland 13 carried by the cover 23. Maximum angular movement of the cam by the stem is controlled with the adjusting screw 14 threadedly received in a second gland entering the end cover from the opposite side thereof. By adjusting the screw 14 the maximum angularity of the cam surface relative to the axis of rotation of the cylinder barrel may be limited. In this manner the maximum volume of the pump or fluid motor may also be varied by changing the piston displacement or the distance into and out of the piston chambers traveled by the pistons.

The outer end of the cover 23 is closed by a plate 15 which is secured thereto by screws or other suitable fastening elements 16.

From Fig. 2 it will be apparent that the face of the cam 62 is also inclined slightly from one side to the other. This inclination is employed to provide a composite cam track which is traversed by the pistons. As shown in Fig. 4 the transverse inclination produces supplemental high and low points designated by letters A and B which are incorporated in the composite cam track. When the device is used as a pump the supplementary high point A will b located in registration with the outlet port substantially at the central part thereof, while the low point B will be correspondingly located with respect to the inlet port. This inclination of the cam plate is maintained throughout all positions of adjustment of the cam to vary the volume of fluid delivered by the pump. It is provided to cause the pistons to move into the piston chambers a slight distance when traveling across the cutofi section between the inlet and outlet ports and to move outwardly of the piston chambers when traveling from th outlet port to the inlet port. The degree of inclination is so selected that the movement of the pistons into the piston chambers while traveling across the cut-off between the inlet and outlet ports will be sufficient to raise the pressure of the fluid in such chambers to the maximum pressure for which the pump has been designed. The movement of the pistons outwardly while the piston chambers are traveling across the cut-off between the outlet and inlet ports will therefore be suflicient to decrease the pressure in the piston chambers from such maximum to substantially atmospheric pressure. It will thus be seen that as the cylinder barrel revolves and the piston chambers move across the cut-off between the inlet port and the outlet port, the second or supplemental inclination of the cam will cause movement of the pistons into the chambers thus increasing the pressure on the fluid therein. As the piston chambers move across the other cut-off, the pistons will be moved outwardly causing the pressure on the fluid in the chambers to fall.

When the pump is operating at its maximum designed working pressure the fluid pressure existing in the piston chamber immediately prior to communication between the piston chambers and the outlet port will be substantially equal. Therefore, when this registration or communication is established, no resulting shock will occur. It will be obvious from the drawing that, even though the volume of the pump is reduced 6 through the adjustment of the cam, the distance travelled by the piston into and out of the piston chambers, while travelling across the cut-off sec-- tions, will remain the same. It is, therefore, essential to provide som means to prevent the pressure in the chambers from exceeding the pressure in the outlet port when the pump is not operating at its maximum rated design pressure. The means selected for effecting this purpose is similar to that shown in the co-pending application Ser. No. 647,872, filed Feb. 15, 1946, of which this application is also a continuation in part. As illustrated in Figs. 3 and 4, this means consists of a valved passage 11 extending between a port '18, formed in the cut-off section between the inlet and outlet ports and the outlet port. The passage 11 contains a springpressed ball valve which is arranged to permit fluid flow from the piston chambers to the outlet port while the ports 55 are moving across the cut-off. This ball valve precludes a reverse flow of fluid, thus preventing the fluid pressure from driving fluid from the outlet port to the piston chambers before the pressure in the chambers reaches that in the outlet port. Communication between the piston chambers and the port 18 is maintained until communication is established between the piston chamber and the outlet port, therefore, if the pressure in the outlet chamber is below the maximum for which the pump has been designed, the fluid displaced by the pistons due to the supplemental inclination of the cam will flow through the passage 1'! after the pressure in the piston chambers increases sufficiently to mov the ball valve 88 off its seat. The pressure in the piston chambers will therefore be precluded from exceeding the pressure in the outlet port.

The action caused by the supplemental inclination when the ports 55 move across the cut-off between the outlet and inlet ports is just reverse of that above described. From Figs. 3 and 4 it will be apparent that a valved passage 8| extends also from a port 82 in the cut-off between the outlet and the inlet to the inlet port. It will be noted that the valve 83 in the passage 8! is reversely arranged compared to valve 89 in the passage 11. This reverse arrangement is employed to prevent the inducement of a pressure in the piston chambers 48 lower than that existing in the inlet port. As soon as a piston chamber 48 communicates with port 82 there will be a tendency for fluid to flow from the inlet port, through passage ill to such chamber if the pressur in the latter is lower than that in the former. If such a pressure relation does not exist, communication will be prevented by the valve 83. Continued movement of the cylinder barrel after such communication is established causes a reduction in pressure in the piston chamber which will be compensated for by a fluid flow through passage 8|. Thus when the particular piston chamber registers with the inlet port, the pressures then existing in these locations will be equal and all objectionable shock will be avoided.

In the modified form shown in Fig. 6, cam plate I6! is mounted for rocking movement about a substantially vertical axis produced by a projec tion I62 formed on the front face of a block I10, which corresponds to the block 10 in the form first described. Th casing of the fluid motor has a pair of piston chambers HI and I12 located on opposite sides of the vertical axis of the casing, these chambers receiving pistons I13. The outwardly projecting ends of these pistons engage 7 therea'r surface'of theplate 'I6I and serve when one or the" other of chambersI'I-I and I12 receives fluid under pressure, to effect rocking movement of the cam plate IGI on the projection H52. The fluid lines I14 and H extend from the chambers HI and I12, respectively, to the inlet and-outlet ports of the pump. In the event the direction of rotation of th pump is reversed, so that the inlet and outlet ports are reversed, the port containing the highest pressure will be connected with one of the piston chambers Ill and H2, and the corresponding piston chamber will receive fluid under high pressure from such port; this introduction of fluid will cause the piston in such chamber to move outwardly, imparting similarmovement to the cam plate IGI. The proper supplemental inclination will thus be imparted to the cam plate to provide for the equalization of pressure between the piston chambers in the cylinder barrel and the inlet and outlet ports. It Will be seen that through the provision of the piston chambers and pistons I'II, I12, and I I3, the pump may be designed for pressure equalization in either direction of operation. With the mechanism shown and described, quiet, shockless operation of the pump will be secured for any desired pressure and either direction of rotation.

The invention is applicable, as shown in Fig. 7, to other types of fluid pressure energy translating devices. In this figure a pump I14 of the type shown in Patent No. 1,931,969, dated Oct. 24, 1933, to Hans Thoma, has been illustrated. This pump includes a driving shaft I15 journalled for rotation in a casing I16. The inner end of the shaft is provided with a driving flange I'I'I having 'a plurality of spaced socket members I18. These socket members receive the ends of connecting rods, the opposite ends of which are connected for universal movement with pistons I89, these pistons being disposed for reciprocatory movement in piston chambers formed in a cylinder barrel IBI. This cylinder barrel is supported for sliding engagement with a valve plate I82 carried by a head I83 which is formed with inlet and outlet passages I84 and I85, respectively, communicating with corresponding passages I86 and I 81 formed in arms I88 and I89 which are rigidly secured at corresponding ends to the head I83. The arms I88 and I89 are journalled for oscillatory movement on a pair of aligned trunnions I90 and I9 I. By moving the head about the axis formed by the trunnions, the angular relation between the cylinder barrel I8I and the flange I" will be varied. The variation of this angle changes the displacement of the pump and thus varies the volume. The pump thus far described is of conventional construction.

It will be noted from Fig. 7 that, in applying the invention to the type of pump shown in this figure, the axis formed by the trunnions is disposed at a slight angle to the axis of rotation of the shaft I15. Normally in a pump of this type, the trunnions are arranged at right angles to the axis of the shaft and when the volume of the pump .is being changed, the head and cylinder barrel are swung about the axis of the trunnions with the axis of the cylinder barrel moving in a plane coinciding with the axis of the shaft. When the volume of the pump shown in Fig. '7 is changed, the axis of the cylinder barrel moves in a plane inclined at an angle to the plane in which the axis of the shaft is located. Due to the inclination of the cylinder barrel in this manner the pistons are caused to move into and out of the chambers in the cylinder barrel during movemen-t'of the piston chamber ports across the cutoff sections of the valve plate, the movement of the pistons into the piston chambers taking place during the travel of the chamber ports across the cut-off between the inlet and outlet port and the movement outwardly taking place during the travel of the chamber ports across the other cutoff portion. These cut-01f portions, as in the form'of the invention first described, are made relatively long so that sufilcient movement of the pistons will take place during the passage of the chamber ports across the same to permit a desired increase of pressure when the piston chambers are approaching the outlet port, and adesired decrease of pressure when such chambers are approaching the inlet port. In this manner the pressures obtaining in the piston chambers as they approach the inlet and outlet ports will conform substantially to the pressures obtaining in these ports. The valve plate will be provided with valved passages, as in the form first described, so that the pressure in the piston chambers will be prevented from exceeding the pressure in the outlet port as they approach the same and from being lower than the pressure in the inlet port when they approach this port. This pressure equalization will eliminate shock and objectionable noise in the operation in the type of pump shown in Fig. 7.

While the mechanism may be modified in many respects, it is intended to embrace all modifications which may be said to fall fairly within the following claims.

'I claim:

1. A fluid pressure energy translating device comprising a cylinder barrel; a valve plate with spaced inlet and outlet ports, said barrel and valve plate being disposed for relative rotary movement; piston means received for reciprocatory movement in the cylinder barrel; cam means for controlling the reciprocation of said pistons, said cam means having a cam track disposed in a plane; and supporting means for said cam means, said supporting means being mounted for pivotal movement about an axis extending at right angles to the axis of said cylinder barrel, said supporting means holding said cam with the plane of said track inclined with respect to the axis of pivotal movement of said supporting means.

2. A fluid pressure energy translating device comprising a cylinder barrel; a valve plate with spaced inlet and outlet ports, said barrel and valve plate being disposed for relative movement; valved passages extending from points on said valve plate in the spaces between said ports to one or the other of said ports; piston means received for reciprocatory movement in said cylinder barrel; cam means for controlling the reciprocations of said pistons, said cam means having a piston engaging track disposed in a plane; support means for said cam means mounted for pivotal movement about an axis extending at right angles to the longitudinal axis of said pump, said support means holding said cam means with the plane of said track inclined with respect to the axis of pivotal movement of said support means; and means for imparting movement to said support means.

3. A fluid pressure energy translating device comprising a cylinder barrel; a valve plate with spaced inlet and outlet ports, said barrel and valve plate being disposed for relative rotary movement; piston means received for reciprocatory movement in the cylinder barrel; planar cam means for controlling the reciprocation of said pistons; and mounting means for said cam means, said mounting means supporting said cam means for movement about an axis extending parallel to the face of said valve plate, the plane of the cam means being inclined with respect to the axis of movement of said cam means.

4. A fluid pressure energy translating device comprising a cylinder barrel; a valve plate with spaced inlet and outlet ports, said barrel and valve plate being disposed for relative rotary movement; piston means received for reciprocatory movement in the cylinder barrel; means for controlling the reciprocation of said piston, said means having piston engaging elements disposed for movement in a path located on a plane; and mounting means for supporting said cylinder barrel and said piston reciprocation controlling means for relative adjustment about an axis ex- REFERENCES CITED The following references are of record in the 10 file of this patent:

UNITED STATES PATENTS Number Name Date 1,081,810 Carey Dec. 16, 1913 1,189,319 Walker July 4, 1916 2,161,143 Doe et a1 June 6, 1939 2,288,768 Zimmermann July 2, 1942 2,299,234 Snader et a1 Oct. 20, 1942 

